1. Field
Exemplary embodiments of the present invention relate to an integrated circuit, and more particularly, to a technology for improving the quality of signals received in an integrated circuit.
2. Description of the Related Art
FIG. 1 is a diagram illustrating a receiver 100, and FIG. 2A and FIG. 2B are diagrams illustrating signals IN, VREF, and OUT inputted/outputted to/from the receiver 100. The input signal IN may have various patterns, but for convenience, FIG. 2A and FIG. 2B illustrate that the input signal IN is inputted with substantially the same pattern (a repetition pattern of ‘H’, ‘L’, ‘H’, and ‘L’) as that of a clock.
Referring to FIG. 1, the receiver 100 compares a voltage level of the input signal IN with a voltage level of the reference voltage VREF and generates the output signal OUT. When the voltage level of the input signal IN is higher than the voltage level of the reference voltage VREF, the receiver 100 generates the output signal OUT at a ‘H’ level, and when the voltage level of the input signal IN is lower than the voltage level of the reference voltage VREF, the receiver 100 generates the output signal OUT at a ‘L’ level.
FIG. 2A is a diagram illustrating the waveforms of the signals IN, VREF, and OUT inputted/outputted to/from the receiver 100 when the level of the reference voltage VREF is relatively low. Referring to FIG. 2A, as the level of the reference voltage VREF becomes low, the high pulse width of the output signal OUT becomes long and the low pulse width of the output signal OUT becomes short. In such a case, since the eye pattern of the output signal OUT widens when the output signal OUT is ‘H’ but it becomes narrow when the output signal OUT is ‘L’, the output signal OUT may be incorrectly recognized at the rear end of the receiver 100.
FIG. 2B is a diagram illustrating the waveforms of the signals IN, VREF, and OUT inputted/outputted to/from the receiver 100 when the level of the reference voltage VREF is relatively high. Referring to FIG. 2B, as the level of the reference voltage VREF becomes high, the low pulse width of the output signal OUT becomes long and the high pulse width of the output signal OUT becomes short. In such a case, since the eye pattern of the output signal OUT widens when the output signal OUT is ‘L’ but it becomes narrow when the output signal OUT is ‘H’, the output signal OUT may also be incorrectly recognized at the rear end of the receiver 100.
As described above, in the receiver 100 that receives the input signal IN by using a scheme of comparing the reference voltage VREF and the input signal IN with each other, the reference voltage VREF is an important factor in deciding the quality of the output signal OUT of the receiver 100.